Wheeled ladder with a weight actuated self-locking wheel thereon

ABSTRACT

The ladder is elevated above its supporting surface and has an arm pivotally mounted on the lower end portion thereof, which is yieldably biased in one angular direction thereof, into a stopped position on the ladder. The arm in turn has a surface engaging wheel thereon, which is rotatably mounted about an axis that is spaced apart from the pivotal axis of the arm, at a point on the arm at which the wheel supports the ladder above the surface in response to the bias on the arm. When the user&#39;&#39;s weight is added to the ladder, the wheel is restrained against rotation by an element which is disposed on the ladder so as to engage the wheel when the arm and the ladder are pivoted in relation to one another in the direction opposed to the bias on the arm. However, there are means on the ladder whereby the restrainer element can be disengaged from the wheel under the condition in which the element and the arm are displaced in relation to one another in the direction opposed to the bias on the arm. Therefore, the wheel can be released for rotation even while the user remains on the ladder.

United States Patent [1 1 Greenleaf [54] WHEELED LADDER WITH A WEIGHTACTUATED SELF-LOCKING WHEEL THEREON [75] Inventor: Jack W. Greenleai,Snohomish,

Wash.

[73] Assignee: Everett Sound Machine Works, Inc.,

Everett, Wash.

[22] Filed: May 22, 1972 [21] Appl. No.: 255,623

[451 my 29, new

Primary Examiner-Reinaldo P. Machado Attorney-Christensen & Sanborn [57]ABSTRACT The ladder is elevated above its supporting surface and has anarm pivotally mounted on the lower end portion thereof, which isyieldably biased in one angular direction thereof, into a stoppedposition on the ladder. The arm in turn has a surface engaging wheelthereon, which is rotatably mounted about an axis that is spaced apartfrom the pivotal axis of the arm, at a point on the arm at which thewheel supports the ladder above the surface in response to the bias onthe arm. When the users weight is added to the ladder, the wheel isrestrained against rotation by an element which is disposed on theladder so as to engage the wheel when the arm and the ladder are pivotedin relation to one another in the direction opposed to the bias on thearm. However, there are means on the ladder whereby the restrainerelement can be disengaged from the wheel under the condition in whichthe element and the arm are displaced in relation to one another in thedirection opposed to the bias on the arm. Therefore, the wheel can bereleased for rotation even while the user remains on the ladder.

11 Claims, 15 Drawing Figures WHEELED LADDER WITH A WEIGHT ACTUATEDSELF-LOCKING WHEEL THEREON FIELD OF THE INVENTION This invention isconcerned with a wheeled ladder, and in particular with a ladder of thisnature in which the wheel automatically locks itself against rotationwhen the users weight is added to the ladder, but which is also equippedwith means whereby the wheel can be released for rotation even while theuser remains on the ladder.

The invention is especially applicable to wheeled ladders which aremovably suspended from a track, such as the main frame ladders used intelephone exchanges, and the shelf ladders used in libraries, shoestores and the like. However, it is also applicable to wheeled ladderswhich are not so suspended, and will be explained hereafter in terms ofa track suspended ladder only for the sake of illustration.

SUMMARY OF THE INVENTION The ladder of the present invention is elevatedabove its supporting surface, and has an arm pivotally mounted on thelower end portion thereof, which is yieldably biased in one angulardirection thereof, into a stopped position on the ladder. The arm inturn has a surface engaging wheel thereon, which is rotatably mountedabout an axis that is spaced apart from the pivotal axis of the arm, ata point on the arm at which the wheel supports the ladder above thesurface in response to the bias on the arm. When the users weight isadded to the ladder, thewheel is restrained against rotation by anelement which is disposed on the ladder so as to engage the wheel whenthe arm and the ladder are pivoted in relation to one another in thedirection opposed to the bias on the arm. However, there are means onthe ladder whereby. the restrainer element can be disengaged from thewheel under the condition in which the element and the arm are displacedin relation to one another in the direction opposed to the bias on thearm. Therefore, the wheel can be released for rotation even while theuser remains on the ladder.

Preferably, the wheel is positively locked against rotation by virtue ofhaving a series of recesses therein which are relatively angularlydisposed about the rotational axis of the wheel, for engagement by a lugwhich is disposed on the ladder so as to engage one of the recesses whenthe arm and the ladder are pivoted in relation to one another in thedirection opposed to the bias on the arm.

To enable the lug to be disengaged under the relatively displacedcondition of the arm, the lug is disposed on a dog which is pivotallymounted on the lower end portion of the ladder in a plane parallel tothat of the arm, and yieldably biased in the same angular direction asthe arm, into a stopped position on the ladder. For ease of operation,moreover, the dog has an actuator connected therewith, which extendslengthwise of the ladder, to points on the upper end portion thereof,and is manually operable at any one of the aforesaid points to pivot thedog in the direction opposed to the bias thereon.

In the presently preferred embodiments of the invention, the dog and thearm are pivotally mounted on one standard of the ladder; the axes of thedog, the arm, and the wheel are all parallel to one another; and therecesses with which the lug is engageable, are defined by a ratchet onone side of the wheel. In those instances where the ladder is movablysuspended from a track, it is preferred to employ a track which iselongated, V-shaped and has a longitudinally extending slot in thebottom thereof, between the angularly related surfaces thereof. Thecarriage for supporting the ladder on the track includes a pair ofrelatively inner and outer rotatably engaged members which are disposedabove the track, and the outer of which has a device suspended therefromin the slot, on which the ladder is hung. The inner member is elongatedon a parallel to the track, and has longitudinally spaced recessestherein, which are disposed at relatively angularly spaced pointsthereabout. A plurality of track engaging wheels are rotatably mountedon the inner member, in the recesses, about axes which extendsubstantially parallel to alternate surfaces of the track, as the wheelsare considered from one recess to the next, lengthwise of the innermember. Consequently, should one or the other surface of the trackbecome deformed with respect to the manufactured V-shaped cross sectionthereof, the hanger device will nevertheless remain freely suspended inthe slot because of the ability of the carriage to accommodate to thedeformation.

BRIEF DESCRIPTION OF THE DRAWINGS These features will be betterunderstood by reference to the accompanying drawings which illustratetwo embodiments of the lock mechanism as it is applied to such a tracksuspended ladder.

In the drawings,

FIG. 1 is a side elevational view of the ladder as it is seen whenemploying one embodiment of the mechanism;

FIG. 2 is a front elevational view of the same;

FIG. 3 is a part side elevational view of the lower end of the ladder,where the mechanism is mounted in conjunction with the wheels thereof;

FIG. 4 is a part cross-sectional view along the lines 4-4 of FIG. 3;

FIG. 5 is a part cross-sectional view along the lines 55 of FIG. 3;

FIG. 6 is a part elevational view of the ladder in the normal unloadedcondition thereof, as it is seen from a point inside thereof, oppositethe lower, wheeled end of the ladder;

FIG. 7 is another such view of the ladder in the loaded conditionthereof;

FIG. 8 is a third such view in the loaded but released conditionthereof;

FIG. 9 is a part perspective schematic view of the lock mechanism forone wheel, when the ladder is in the normal unloaded condition thereof;

FIG. is another such view of the mechanism when the ladder is in theloaded condition thereof;

FIG. II is a part perspective, lower end view of the ladder whenemploying the other embodiment of the mechansim;

FIG. 12 is a partially removed, part perspective view of the carriageand the track for the ladder;

FIG. 13 is a cross-sectional view along the lines 13-13 of FIG. 12;

FIG. 114 is another such view along the lines l414 of FIG. 12; and

FIG. is a schematic view corresponding to that of FIG. 13, butillustrating the operation of the carriage when the track is deformed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, itwill be seen that the ladder comprises a pair of spaced, parallel, endmitered standards 2 which are interconnected by a flight of spaced,parallel steps 4 that are tilted in relation to the standards to assumea horizontal disposition when the ladder is in the normally inclined,upright, suspended, selectively mobile condition thereof.

To maintain this condition, the ladder is suspended on a gantry-liketrolly device 6 which is suspended in turn on a roller-borne carriage 8housed within a horizontally disposed track 10 having a slot 12 in thebottom thereof, for the sleeved hanger 14 of the trolly 6. In addition,the ladder is elevated above the floor l6 therebelow, and is supportedon a pair of wheels 18 which are outriggered from the standards toreleasably lockingly engage with the ladder when a weight is added tothe flight of steps thereon.

Referring firstly to this latter feature in particular, it will be seenthat the standards 2 have longitudinally extending plates 20 scabbed onto the inside lower end surfaces thereof, and the plates 20 in turn havebosses 22 on the insides thereof, within which a bushed shaft 24 isjoumaled in a horizontally disposed, crosswise condition between theplates. The bosses 22 are disposed at corresponding points on thechamfered, relatively forward, lower end corners 26 of the plates, andthe shaft 24 passes through the plates 20 at these points, and projectsoutwardly therefrom, where, welded to the outlying ends of the shaft, isa pair of correspondingly U-shaped brackets 38, each having a barlikethumb upstanding thereon. The brackets 28 are inverted to the front andoriented in a crosswise plane generally perpendicular to the ladder, andare appended to the shaft 24 at points on the inside legs 28' thereof,adjacent the junctures of the legs with the bight portions 28" of thebrackets. The thumbs 30 are also disposed on these legs, at pointsadjacent the shaft, and each thumb has a stud bolt 32 thereon, whichprojects inwardly of the ladder and passes through a transverselyoriented slot 34 in the adjacent plate 20. In addition, the inside andoutside legs 28' and 28" of each bracket are joined by an axle 36,adjacent the ends of the legs, and one wheel 18 is rotatably mounted onthe axle, between the legs. The wheel 18 has an annular ratchet 38secured to the inside face thereof, concentric with the axle, and theratchet has internally oriented teeth 40 thereon, which cooperate with alug 42 on the midportion of a dog 44 which is pivotally mounted to a pin45 on the plate 20, in juxtaposition with the wheel, below the insideleg 28 of the bracket. One end of the dog is under the control of acoiled spring 46, and the other is under the control of a levermechanism 48 which operates to pivot the dog against the bias of thespring 46. The spring is interconnected between a stud bolt 50 on theone end of the dog, and another such bolt 52 located on the inside faceof the plate, at a point to the rear of the shaft. The lever mechanism48 includes an oblique-angled bar lever 54 which is pivotal about aspindle 56 mounted below the underside of the first step, and which isinterconnected to the other end of each dog by means of a pair ofoblique-angled links 58 that angle down to the ends of the dogs from thecrock of the lever 54. The lever is operated from one of a number ofpoints on the ladder, by means of a partially housed Bowden wireassembly 60 extending up the length of the ladder from the tip of thelever, to a connecting point 61 adjacent the top thereof, there beingguides 62 cantilevered from various steps of the ladder to support theassembly 60.

Referring now to FIGS. 6-8, it will be seen that from this point ofview, the brackets 28 are loaded in a counterclockwise direction aboutthe shaft, by means of other coiled springs 64 which are secured to thebolts 32 of the thumbs at one end, and at the other end, to a pair ofadjustable take-up devices 66 each comprising a threaded rod 68 which isthreadedly engaged in an apertured flange 70 on the rearwardly facingedge of the plate. Thus, in the normal, unloaded condition of theladder, the bracket 28 and wheels 18 maintain a posture with respect tothe plates and dogs, such that the lugs 42 on the dogs are disengagedfrom the ratchet 38, leaving the wheels free to turn. See FIG. 6.However, when the weight of the user is added to the ladder, the wheelsand brackets are caused to pivot in the clockwise direction about theshaft, against the bias of the springs 64, and with the result that thelugs on the dogs engage in recesses 38' of the ratchets. See FIG. 7. Atthis point, therefore, the wheels are no longer free to turn, and theladder is thus locked in position by the continued presence of the userthereon. Should the user choose to disengage the lugs, however, he maygrab the cable 72 of the Bowden wire assembly, and pivot the dogs in theclockwise direction, so as to effect disengagement of the lugs as inFIG. 8. This may be accomplished, moreover, even while the user remainson the ladder, and so long as he continues to raise the dogs with thecable, he may propel himself and the ladder relative to the floor 16thereunder.

Ordinarily, the take-up devices 66 are adjusted to a point at which thelugs 42 will engage with the ratchets 38 only after the man has assumeda position on the second step up from the bottom of the ladder, orhigher.

A part annular fender 74 of U-shaped cross section, is secured to theoutside leg 28" of each bracket for purposes of housing the upper sidesof the wheels. A rail 75 on the right-hand standard assists in climbingthe ladder.

In the embodiment of FIG. 11, each wheel 76 has an externally toothedratchet 78 on the outside face thereof, and the ratchet cooperates witha lug 80 on a dog 82 which is pivotally interconnected between a pair ofspaced parallel plates 84 scabbed to the end of each standard 2' of theladder. The plates have an axle 86 joumaled therebetween, and the partannular fender housing 88 of the wheel is outriggered from the axle, andloaded in the counterclockwise direction of the Figure by a stopped,spring-loaded lever 90 on the axle, the spring for same being seen at91. The loading on the dog 82 is provided by another spring 92 which issecured to an arm 94 on a bushing 96 that is fixed between the plates84, with the axle 86 passing therethrough.

Referring next to the carriage 8 and the track 10 for the ladder, itwill be seen that the track 10 has oppositely inclined surfaces 98 onthe V-shaped bottom thereof, to either side of the slot 12, and thecarriage 8 comprises an elongated cylindrical bolt 100 which hassemicircular sections thereof removed at spaced intervals therealong, toform a corresponding number of flats 102 therein, which are disposed indiametrical planes of the bolt that are perpendicular to alternatesurfaces 98 of the track. The flats 102 have narrow cylindrical rollers104 trunioned thereon, and the rollers ride on alternate surfaces of thetrack to maintain the hanger 14 of the trolly in a central plane of theslot 12. This is true, moreover, even where the bottom of the trackgives way on one side or the other of the trolly, as in FIG. 15. In sucha case, even though the righthand side of the bottom is deformed fromthe manufactured condition of the track, the carriage still maintainsthe centralized disposition of the hanger, due to the fact that the bolt100 is rotatably journaled in the sleeves 106 of the hanger, the sleevesbeing spaced apart to accommodate the intermediate flat 102 and roller104, as seen in FIG. 12.

What is claimed is:

1. In combination, a ladder elevated above its supporting surface, anarm pivotally mounted on the lower end portion of the ladder, which isyieldably biased in one angular direction thereof, into a stoppedposition on the ladder, and which has a surface engaging wheel thereon,which is rotatably mounted about an axis that is spaced apart from thepivotal axis of the arm, at a point on the arm at which the wheelsupports the ladder above the surface in response to the bias on thearm, means for restraining the wheel against rotation when the usersweight is added to the ladder, including an element which is disposed onthe ladder so as to engage the wheel when the arm and the ladder arepivoted in relation to one another in the direction opposed to the biason the arm, and means on the ladder whereby the restrainer element canbe disengaged from the wheel when the element and the arm are displacedin relation to one another in the direction opposed to the bias on thearm, so that the wheel can be released for rotation even while the userremains on the ladder.

2. The combination according to claim 1 wherein the wheel has a seriesof recesses therein which are relatively angularly disposed about therotational axis of the wheel, and there is a lug which is disposed onthe ladder so as to engage one of the recesses when the arm and theladder are pivoted in relation to one another in the direction opposedto the bias on the arm.

3. The combination according to claim 2 wherein the lug is disposed on adog which is pivotally mounted on the lower end portion of the ladder ina plane parallel to that of the arm, and yieldably biased in the sameangular direction as the arm, into a stopped position on the ladder.

4. The combination according to claim 3 wherein the dog has an actuatorconnected therewith, which extends lengthwise of the ladder, to pointson the upper end portion thereof, and is manually operable at any one ofthe aforesaid points to pivot the dog in the direction opposed to thebias thereon.

5. The combination according to claim 3 wherein the dog and the arm arepivotally mounted on one standard of the ladder.

6. The combination according to claim 5 wherein the axes of the dog, thearm, and the wheel are all parallel to one another.

7. The combination according to claim 3 wherein the recesses with whichthe lug is engageable are defined by a ratchet on one side of the wheel.

8. The combination according to claim 1 wherein the ladder is movablysuspended from a track.

9. The combination according to claim 8 wherein the track is elongated,V-shaped, and has a longitudinally extending slot in the bottom thereof,between the angularly related surfaces thereof, and there is a carriageon the track including a pair of relatively inner and outer rotationablyengaged members which are disposed above the track, and the outer ofwhich has a device suspended therefrom in the slot, on which the ladderis hung, the inner member being elongated on a parallel to the track,and having longitudinal spaced recesses therein, which are disposed atrelatively angularly spaced points thereabout, and a plurality of trackengaging wheels thereon, in the recesses, which are rotatably mountedabout axes that extend substantially parallel to alternate surfaces ofthe track, as the wheels are considered from one recess to the next,lengthwise of the inner member.

10. In combination, a standard elevated above its supporting surface, anarm pivotally mounted on the lower end portion of the standard, which isyieldably biased in one angular direction thereof, into a stoppedposition on the standard, and has a surface engaging wheel thereon,which is rotatably mounted about an axis that is spaced apart from thepivotal axis of the arm, at a point on the arm at which the wheelsupports the standard above the surface in response to the bias on thearm, means for restraining the wheel against rotation when a weight isadded to the standard, including an element which is disposed on thestandard so as to engage the wheel when the arm and the standard arepivoted in relation to one another in the direction opposed to the biason the arm, and means on the standard whereby the restrainer element canbe disengaged from the wheel when the element and the arm are displacedin relation to one another in the direction opposed to the bias on thearm, so that the wheel can be released for rotation even while theweight remains on the standard.

111. In combination, a track which is elongated, V- shaped, and has alongitudinally extending slot in the bottom thereof, between theangularly related surfaces thereof, and a carriage for supporting a bodyon the track, including a pair of relatively inner and outer rotatablyengaged members which are disposed above the track, and the outer ofwhich has a device suspended therefrom in the slot, on which the body ishung, the inner member being elongated on a parallel to the track, andhaving longitudinally spaced recesses therein, which are disposed atrelatively angularly spaced points thereabout, and a plurality of trackengaging wheels thereon, in the recesses, which are rotatably mountedabout axes which extend substantially parallel to alternate surfaces ofthe track, as the wheels are considered from one recess to the next,lengthwise of the inner member.

t i l t t

1. In combination, a ladder elevated above its supporting surface, anarm pivotally mounted on the lower end portion of the laddEr, which isyieldably biased in one angular direction thereof, into a stoppedposition on the ladder, and which has a surface engaging wheel thereon,which is rotatably mounted about an axis that is spaced apart from thepivotal axis of the arm, at a point on the arm at which the wheelsupports the ladder above the surface in response to the bias on thearm, means for restraining the wheel against rotation when the user''sweight is added to the ladder, including an element which is disposed onthe ladder so as to engage the wheel when the arm and the ladder arepivoted in relation to one another in the direction opposed to the biason the arm, and means on the ladder whereby the restrainer element canbe disengaged from the wheel when the element and the arm are displacedin relation to one another in the direction opposed to the bias on thearm, so that the wheel can be released for rotation even while the userremains on the ladder.
 2. The combination according to claim 1 whereinthe wheel has a series of recesses therein which are relativelyangularly disposed about the rotational axis of the wheel, and there isa lug which is disposed on the ladder so as to engage one of therecesses when the arm and the ladder are pivoted in relation to oneanother in the direction opposed to the bias on the arm.
 3. Thecombination according to claim 2 wherein the lug is disposed on a dogwhich is pivotally mounted on the lower end portion of the ladder in aplane parallel to that of the arm, and yieldably biased in the sameangular direction as the arm, into a stopped position on the ladder. 4.The combination according to claim 3 wherein the dog has an actuatorconnected therewith, which extends lengthwise of the ladder, to pointson the upper end portion thereof, and is manually operable at any one ofthe aforesaid points to pivot the dog in the direction opposed to thebias thereon.
 5. The combination according to claim 3 wherein the dogand the arm are pivotally mounted on one standard of the ladder.
 6. Thecombination according to claim 5 wherein the axes of the dog, the arm,and the wheel are all parallel to one another.
 7. The combinationaccording to claim 3 wherein the recesses with which the lug isengageable are defined by a ratchet on one side of the wheel.
 8. Thecombination according to claim 1 wherein the ladder is movably suspendedfrom a track.
 9. The combination according to claim 8 wherein the trackis elongated, V-shaped, and has a longitudinally extending slot in thebottom thereof, between the angularly related surfaces thereof, andthere is a carriage on the track including a pair of relatively innerand outer rotationably engaged members which are disposed above thetrack, and the outer of which has a device suspended therefrom in theslot, on which the ladder is hung, the inner member being elongated on aparallel to the track, and having longitudinal spaced recesses therein,which are disposed at relatively angularly spaced points thereabout, anda plurality of track engaging wheels thereon, in the recesses, which arerotatably mounted about axes that extend substantially parallel toalternate surfaces of the track, as the wheels are considered from onerecess to the next, lengthwise of the inner member.
 10. In combination,a standard elevated above its supporting surface, an arm pivotallymounted on the lower end portion of the standard, which is yieldablybiased in one angular direction thereof, into a stopped position on thestandard, and has a surface engaging wheel thereon, which is rotatablymounted about an axis that is spaced apart from the pivotal axis of thearm, at a point on the arm at which the wheel supports the standardabove the surface in response to the bias on the arm, means forrestraining the wheel against rotation when a weight is added to thestandard, including an element which is disposed on the standard so asto engage the wheel when the arm and the standard are pivoted inrelation to one another in the directIon opposed to the bias on the arm,and means on the standard whereby the restrainer element can bedisengaged from the wheel when the element and the arm are displaced inrelation to one another in the direction opposed to the bias on the arm,so that the wheel can be released for rotation even while the weightremains on the standard.
 11. In combination, a track which is elongated,V-shaped, and has a longitudinally extending slot in the bottom thereof,between the angularly related surfaces thereof, and a carriage forsupporting a body on the track, including a pair of relatively inner andouter rotatably engaged members which are disposed above the track, andthe outer of which has a device suspended therefrom in the slot, onwhich the body is hung, the inner member being elongated on a parallelto the track, and having longitudinally spaced recesses therein, whichare disposed at relatively angularly spaced points thereabout, and aplurality of track engaging wheels thereon, in the recesses, which arerotatably mounted about axes which extend substantially parallel toalternate surfaces of the track, as the wheels are considered from onerecess to the next, lengthwise of the inner member.